I created an account on this forum just to post a reply here in case any others find it useful.
I received my AOR Nov 5th and tried every single day since that date to register on the citizenship tracker account. But I kept getting the same "wrong details" type of error even though my details were as per IRCC's email. Filling out web form (technical difficulties category) was also not helpful, I did get a response from an agent but it did not even address the registration issue, just a standard response to go to the help centre.
I just tried registering today and I failed again
AND THEN
I tried registering via the browser on my phone (android using chrome browser in my case) and the registration went through immediately! I received my security code in my email within a few minutes and can now successfully sign in, even via my computer.
tl;dr - if you cant register, try registering using your phone. that worked for me